Titanium and titanium alloy with lubricant coated surface

ABSTRACT

Minimizing the galling of titanium (or alloys) in sea water by first providing a conversion coating such as an impregnated coating of polytetrafluoroethylene, then overlaying with a coating of molybdenum disulfide and a final outer coating of asphaltic grease. An apparatus for evaluating galling of titanium wires under extreme pressure wherein a rope or wire is supported on a reciprocating weighted crank arm and abuts a stationary wire. The weighted arm applies the necessary pressure and imparts relative motion between the wires, and thereby causes repeatable galling results.

United States Patent Ohlbaum et al.

[ 51 Apr. 4, 1972 [54] TITANIUM AND TITANIUM ALLOY WITH LUBRICANT COATED SURFACE [72] Inventors: Robert A. Ohlbaum, Silver Spring; Charles A. Zanis; Joseph R. Crisci, both of Bowie, all of Md.

[73] Assignee: The United States of America as represented by the Secretary of the Navy 221 Filed: Apr. 30, 1970 211 Appl.No.: 33,454

OTHER PUBLICATIONS Fitzsimmons et al., Thin Films of PTFE Resin as Lubricants and Preservative Coatings for Metals, NRL Report, 4753, June 15, 1956, p. 16.

Primary Examiner-William D. Martin Assistant ExaminerRalph Husack Attorney-Richard S. Sciascia, Louis B. Applebaum and Ernest F. Weinberger [S 7] ABSTRACT Minimizing the galling of titanium (or alloys) in sea water by first providing a conversion coating such as an impregnated coating of polytetrafluoroethylene, then overlaying with a coating of molybdenum disulfide and a final outer coating of asphaltic grease. An apparatus for evaluating galling of titanium wires under extreme pressure wherein a rope or wire is supported 'on a reciprocating weighted crank arm and abuts a stationary wire. The weighted arm applies the necessary pressure and imparts relative motion between the wires, and thereby causes repeatable galling results.

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2 Sheets-Sheet l lm ywm Patented April 4, 1972 3,653,940

2 Sheets-Sheet 2 TITANIUM AND TITANIUM ALLOY WITH LUBRICA COATED SURFACE The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION practice to employ readily available coatings of various plastics and lubricants. Such materials, either alone or in com bination, have been unsatisfactory in that, although they reduce titanium galling in air, they are almost entirely ineffective when the abrading wires are subjected to a salt water environment.

SUMMARY- OF THE INVENTION The general purpose of this invention it to provide a titanium coating that has all the advantages of prior art techniques and has none of the above described disadvantages. To attain this, the present invention provides a unique combination of three individual coatings wherein the base coat is an impregnation of Teflon, the intermediate coating is molybdenum disulfide and an outer coating is of asphaltic grease, whereby galling at extreme pressures and in sea water is substantially reduced.

An object of the present invention is to provide a reliable, simple, inexpensivecoating for titanium surfaces which may be readily applied and reduces galling.

Another object is to provide a special lubricating composition for titanium surfaces for the reduction of galling in sea water.

Other objects and many of the attendant advantages of this.

invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENT In the embodiment of the galling test machine of FIG. 1, a variable speed drive motor rotatably drives an eccentric cam 11 via shaft 12 which in turn is connected through shaft 13 to crank arm 14. This crank arm reciprocates between bearings 15 and 16 and provides simple harmonic motion. A cycle counter 17 senses the number of reciprocations of the arm and may be electrically connected to the motor 10 so as to terminate the arm movement after a preset number of cycles. The arm itself is unsupported vertically and carries at its far end a weight member 18 so as to pivotabout the shaft 13 and provide an additional downward force. Disposed on the underside of the arm opposite the member 18 and attached to the arm is one of the wires 19, to be evaluated for galling.

As illustrated in FIG. 2. the motor 10 and the bearing 15 and 16 are supported by base 20, which also carries block 21 directly beneath weight 18. Disposed on the upper surface of block 21 is a stationary wire 22, which contacts wire 19 and rubs thereagamst as the arm 14 reciprocates. FIG. 3 depicts the spatial relationship of the wires or ropes under test. The moving wire 19 is shown in both of its terminal positions and the areas marked thereon indicate where the galling is taking place.

Since in one particularimportant application, titanium alloy wire rope is subjected to extreme galling pressure, this testing apparatus was designed to apply high pressure and may be operated in a sea water atmosphere. Additionally, wire ropes are fabricated under certain standards which set the angular relations between the strands and the ropes used in specific configurations. This determines the angular separation between the wires 19 and 22 which, in the illustrated simulation, is approximately 65.

Gallings tests ofvarious representative coatings applied to a titanium alloy (Ti l3V-ll Cr-3Al) were performed and the results are tabulated in FIG. 4. These results clearly indicate the superior quality of applicants coating in reducing galling in view of the average number of cycles required to start galling. Applicants first impregnate the titanium wire with polytetrafluoroethylene (PTF E hereinafter referred to under its trade mark designation Teflon) by standard methods described by the manufacturer and supplier. This initial coating is of the conversion type and other materials such as fluorides could be used to control the porosity. This undercoating, which may also be Teflon is then covered with a layer of molybdenum disulfide which is overlayed with a common asphaltic grease.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

We claim:

1. A metal shape selected from the class consisting of titanium and titanium alloys having a first coating consisting essentially of polytetrafluoroethylene applied directly on the surface of the metal shape to control porosity, a second coating consisting essentially of molybdenum disulfide, and'an outer coating of asphaltic grease.

2. The metal shape of claim 1 wherein said first coating is an impregnation of polytetrafluoroethylene. 

2. The metal shape of claim 1 wherein said first coating is an impregnation of polytetrafluoroethylene. 